Encapsulated/Conditiond Crawlspace

[USAFpj]

So we're on our way with the construction of a new house. The budget didn't allow for a basement, so we're going to go with a taller crawlspace foundation. If doing it, I want to do it right, so being in the humid South, I'm investigating the virtues of an encapsulated, ventless, and conditioned crawl. I've read a lot of great statistics on how this is the way to go in the Southeast, but they all seem to be from the guys selling them!

My contractor has a quote of $4,300 to use "20mil liner, insulate foundation walls, sealant, and HVAC zone for climate control". It seems to me that 70% of homes in the South have a typical crawl, and is there a necessity for this? This should be our forever home, so I want to do it right the first time, but could also put that $$ towards a new shop as well. Priorities should be proper grading and keeping water away via gutters.

Anyone care to give an opinion??

 

[dmccarty]

If you think your inspectors will allow the conditioned crawlspace, I would do it AND THE ATTIC.

Go read what Joe Lstiburek, Joseph Lstiburek, has to say. He is a PHd in Building Science, a couple of engineering degrees and is a PE. I built our house based on the design details in one of his books. He has four books that give design details for different climates in the US, Builder's Guides. I don't know if your area would need the Hot Humid Climate or Mixed Humid Climate book

He has a bunch of information here, Conditioned Crawlspaces about conditioned crawl spaces.

Lstiburek knows what he is talking about.

Later,
Dan

 

[EddieWalker]

I think it's a waste of money. In every house that I've seen it attempted, there are so many holes in the insulation, gaps where its either fallen apart or been taken apart that it's not doing anything.

If I understand this correctly, the theory is to insulate the bottom of the house from the elements to make it easier to maintain inside temperatures and humidity. The question is, how much does this accomplish? The two most important and noticeable areas are keeping the wind out with house wrap, and maximizing your attic space. Nothing else even comes close to creating noticeable results. Then going with good quality windows that are properly sealed. It's shocking how many windows I come across that are not sealed, and even have total air gaps between the outside and interior trim. Air getting through your walls is just like being hosed down by water. It's fast and very hard to fight.

Insulating your walls and good doors add up to the equation, but the results are minimal. You will only get so much out of the walls because heat and cold go up and down. Wind comes through sideways. While the temperature of the ground around the sides of your house will vary a lot, under your house it stays pretty constant if it's dry. If it's wet, you got other issues and adding insulation to a wet area is only going to create a nightmare down the road.

I love reading the articles in the magazines like Fine Homebuilder, where they go out and do everything possible to super insulate the house. Two rows of stud that do not touch each other, mixing foam and fiberglass layers, triple and quadruple pain glass and taping every seal possible. The results are impressive, but when compared to what you get from just doing the basics and spending tens of thousands of dollars less, they don't make any sense. Every time you open the outside door you cause more heat or cooling loss then all that extra stuff is supposed to solve.

It reminds me of a friend who paid $500 for a titanium bicycle seat because it was a few ounces lighter then the one he already had. He felt it was a great deal and that it increased his times when going for a ride. He was also overweight and he has never been in a race in his life. It was all about personal feel good. Same thing growing up working on cars. How much money was spent on headers, carburetor's and manifolds to get a couple more horsepower just to drive around town? I know that in my case, if I had left everything stock, I would have more cash in my pocket with the same results. Most energy savings stuff is just a way to spend a lot of extra money to feel good. The point of going overboard and throwing money away happens when you start trying to get that one extra half a percent improvement.

Eddie

 

[NY_Yankees_Fan]

Eddie, We are buying an 80 year old home with no attic insulation. The attic is completely open and assessable. What is the best insulation for the$? Blown in cellulose, fiberglass or fiberglass up to the top of the joist and a fiberglass over the top of the joist. Any other types, I think foam would be too much. Sorry for stealing the thread......

 

[rrrkkk]

Try this website this guy is very good. I have been to his seminars, he doesn't mind a call and will steer you straight!
Official Website of Doug Rye

 

[DFB]

Is there any local building code specs on crawl space insulation where you are? Just my experience from living in a cold climate if the outside temp should stay below 40F degrees for any length of time you would probably appreciate having the floor insulated if there is no heat under it.

Now around here current building energy codes requires insulation under living spaces. Even with full 8 ft deep foundation the general temperature hoovers only around 50 in the average insulated wall basement usually only ever getting into the 40's in an totally unheated space in the very coldest weather. But they still want you to insulate your first floor joists full depth (be like an R30 value). What gets me with that is most homes have the heat source, usually a hydronic boiler system in the basement so now your blocking any residual heat from warming your floor. :confused3:

I cant answer your question what you should do because obviously I have no experience with how warm or cold your living environment is. I do have warm floors in cold weather around 70 all the time with radiant floor heat. Works for me...my other place had no basement heating system only a first floor wood stove..dang were those uninsulated wood floors ever cold!

 

[vabiker23518]

When I had my cabin built in 2009, I went with the encapsulated crawl space. So far it has worked well with no problems. Dry as a bone. Very satisfied with the results in humid Virginia.

 

[truckdiagnostics]

If i ever built again, no basement and no crawl space, I would still use footings, fill it with sand back fill compact and pour concrete. You could use in floor to heat the concrete, and where you are at not going to take much of a boiler they make instant hot water heater that you can use as boiler also. I agree with Eddie maintaining that vapor barrier over time.... here we put plastic vapor barrier right under the drywall and every time you hang a picture you poke a hole in it, so over time. My opinion crawl space an issue, build with out one.

 

[EddieWalker]

Eddie, We are buying an 80 year old home with no attic insulation. The attic is completely open and assessable. What is the best insulation for the$? Blown in cellulose, fiberglass or fiberglass up to the top of the joist and a fiberglass over the top of the joist. Any other types, I think foam would be too much. Sorry for stealing the thread......

Nothing gives you bigger bang for the buck then blown in insulation. Just be sure that it does not block the soffit vents. R60 is about as good as you can get, and that's achieved with about 24 inches. It's an easy do it yourself if you don't mind sitting in the attic holding the hose for several hours. Feeding the machine is easily done by kids or the wife.

Your goal is to get as high an R value as you can. Spray foam will give it to you with a few inches at a much greater initial cost. Just be careful if you go with foam and not use open cell. That will trap water between the foam and the roof, which will lead to early failure of shingles and decking. Closed cell foam is expensive!!!!

Eddie

 

[tman1020]

Insulated and conditioned crawlspaces are all the rage now. Done properly insulating a crawl is not a bad thing. As far as adding heat to your crawlspace just doesn't make sense to me unless you're looking for a way to waste money and energy.

One thing a lot of people overlook is indoor air quality. It is a huge issue and many times in modern construction houses can get too tight and not allow enough fresh air in. In the event of this outside air mixers are added to HVAC systems.

The reason I bring this up is because if you have a insulated and conditioned crawlspace that is one more area of concern. With a vented crawlspace radon is less of a concern. So in conclusion insulate if you want run supply lines if you want but at least put in the vents in case you change your mind down the road you can always block them off or close them.